Nitrosamines have been implicated as carcinogens causing liver tumors in rats. It is well known that secondary amines in the presence of nitrosating agents are converted to nitrosamines. Primary and tertiary amines convert to secondary amines under certain conditions i.e. in the presence of catalyzing agents such as formaldehyde. Nitrates, nitrites and other oxides of nitrogen react readily under such conditions to form nitrosamines. Since nitrogen compounds, including nitrites, are ubiquitous in nature, there is presented the possiblity of nitrosamine formation wherever amine compounds are present.
It is not known whether topically applied products (creams, lotions etc.) containing nitrosamines will in fact cause carcinogenicity. Our present laws are such, however, that any product known to produce any type of cancer in any animal is under scrutiny. As a result, investigators are actively studying the potentially carcinogenic effect of the topical application of products containing nitrosating agents. It would of course be desirable to be able to prevent the formation of such carcinogens in topically applied products.
Certain compounds are known to act as prophylactics in preventing the formation of nitrosamines. In the meat industry the conversion of amines of nitrosamines has been overcome to a great extent by the addition of inhibitors to meat products. The primary inhibitor used is ascorbic acid. Other inhibitors are alpha tocopherol, ascorbyl palmitate, ascorbates and isoascorbates.
It is known that inorganic nitrates and nitrites are unstable oxidizers at elevated temperatures and when in contact with organic materials their acidic decomposition products are likely to become reactive in situ. Some unsaturated hydrocarbons, in particular those having more than one non-conjugated double bond are easily attacked by these acidic products as well as the salts with weak bases. This effect was applied to the stabilization of an ammonium nitrate propellant system where the unsaturated hydrocarbons used included digeranyl, squalene and lycopersen. See for example U.S. Pat. No. 3,215,573 incorporated herein by reference.